The invention relates to a multilayered film element comprising a first component, more particularly an RFID antenna in the form of a multilayered film element, and to a method for fixing a second component on such a multilayered film element (RFID=Radio Frequency Identification).
An RFID transponder comprises at least one antenna and an electronic microchip, called “chip” for short, which are arranged on a carrier. In one known method for producing an RFID transponder, firstly an antenna substrate, i.e. a multilayered film element comprising a carrier substrate and at least one electrically conductive layer as RFID antenna, is provided and then the antenna is electrically connected to a transponder chip. One widely used way of mounting the chip on the antenna substrate is flip-chip bonding. In this case, the chip is provided with contact bumps on its active contact-making side (“chip bond pads”), turned over—hence the name flip-chip—, aligned and arranged with its contact-making side on corresponding chip contact areas (“substrate bond pads”) of the antenna substrate such that an electrically conductive contact is produced between the chip and the antenna. In an alternative embodiment, the chip can be mechanically fixed and electrically contact-connected on a wiring element, for example a so-called “strap”, wherein the wiring element for its part has contact elements which are arranged on corresponding chip contact areas (“substrate bond pads”) of the antenna substrate, such that an electrically conductive contact is produced between the chip and the antenna.
A heating device, e.g. a heatable pressure plunger (thermode), can be brought into contact with one or more components in order that the antenna and the chip or the antenna and the wiring element with the chip mounted thereon are permanently mechanically connected to one another. In this case, suitable adhesives or solders can be employed as “connecting means”. By way of example, adhesive applied previously in the region of the chip contact areas can be activated, e.g. cured, after the positioning of the flip-chip or of the wiring element with the chip mounted thereon on the antenna substrate, by means of a thermode. In this way, mechanical fixing and electrical contact-making are effected during flip-chip mounting or the mounting of the wiring element with the chip mounted thereon in a single process step. Moreover the electrical contact locations are protected against environmental influences by virtue of being embedded in the adhesive. Flip-chip mounting is described in DE 10 2004 059 281 B3 and DE 10 2007 058 802 B3.
During connecting processes in which components are connected to multilayered film elements of this type, e.g. during the chip bonding of transponder chips or wiring elements with a chip mounted thereon on multilayered film elements of this type, more particularly on RFID antennas in the form of multilayered film elements, it has been found, then, that when using substrates composed of readily meltable materials, e.g. PVC-ABS, as a carrier for the RFID antenna, adhering deposits of these materials on a thermode can occur (PVC=polyvinyl chloride; ABS=acrylonitrile-butadiene-styrene copolymer). However, adhering deposits of material on the thermode prevent a uniform and whole-area contact between the thermode and the substrate, which leads to production faults.
US 2010/147958 A1 relates to a method for producing a device comprising a transponder antenna which is connected to contact areas. A thermode is used in this case. In one embodiment, an antenna cable is brought into contact with the dielectric layer. The rear side of the dielectric layer can then be contacted with a thermode. The antenna cable is fixed in interaction with the thermode by a plunger.
DE 10 2007 004642 A1 relates to a flexible printed circuit board film comprising two copper plies. In one embodiment, a first copper ply with electrical contacts is situated on the top side. Situated on the rear side is a second copper ply, thereon an adhesive layer and thereon a polyimide layer, which functions as a thermode contact layer with the surface.
DE 196 47 845 A1 discloses a method for producing a smartcard. A semiconductor chip situated on a module is mechanically and electrically contact-connected in a cutout of a cable carrier. Said cutout has connection areas which are part of or lead to an inductive information transmission device arranged in the smartcard. The semiconductor chip can be situated on a carrier substrate having at its underside contact sides which lead to the connection areas of the inductive information transmission device. For cohesively connecting said contacts to the connection areas, the module is inserted with the carrier substrate rear side first into the cutout of the card body and soldered by means of thermodes, for instance.